When wooden boxes, drawers, and the like are made, substantial attention must be paid to the manner in which the pieces of wood that form the sides of the box are joined together, typically at a 90° angle. Woodworkers are skilled at making a number of types of joints, including dovetail joints and box joints, in order to permit assembly of the box in a manner that results in a solid and secure joining of the sides. The primary difference between a box joint and a dovetail joint is that in a box joint, the tails and pins are square cut all the way through the joint, while in a dovetail joint, the cuts are made at interlocking angles.
Conventionally, box joints are formed in one of four ways. The cuts can be made using a table saw, with a standard flat-top blade with a kerf width, for example, of ⅛″, with multiple passes made to create each finger. This presents a number of disadvantages. This method is time-consuming; a 6-inch-deep box might require 12 fingers per side, or 48 per box, which could be 144 cuts for each box. Also, because a large number of cuts are being made, there is excessive wear on the blade as well as the possibility of a varied groove depth.
Another method of cutting box joints is to use a table saw with a stacked dado cutter. This method solves the problem of repetitive cuts with a table saw and standard blade, but other problems arise in application. The dado cutter must be shimmed to the appropriate cut width. More significantly, the grind geometry of a dado cutter is not designed to give the cleanest cut when applied to the orientation of the box joint; a dado is instead designed to cut grooves in a ripping orientation or a cross-cutting orientation. Additionally, scoring at the corners of the dado would be highly evident on a box joint.
A third method of cutting box joints is to dispense with the table saw entirely and instead use a straight bit on a router table. However, in such an arrangement the wood is on end, with its narrow edge against the fence. Because the cutting rotation in a router is oriented differently from the cutting rotation in a table saw, this arrangement is more susceptible to slight movements of the wood from perfect contact with the fence. Any slight movement of the wood workpiece will be revealed in the cut.
Still another method of cutting box joints is to use a dovetail jig. However, these methods are expensive and complex, and the quality of the cut with a rotating bit is not as good as that made with a saw blade. This method is therefore generally regarded as inferior.
Additionally, these joints could be cut by hand using a saw and a chisel, but this is an extremely time-consuming process that requires a great deal of skill and practice.
What is needed, therefore, is a box joint cutting system that does not require multiple passes for each finger, that produces smooth, flat-bottom grooves, and that may be easily set up to produce cuts of standard sizes.